tested. RH fluctuated between 30% and 70% without any influence on
the interior climate. The boxes were well sealed to prevent leakage.
The Mauritshuis microclimate box now uses polycarbonate sheets
as a backing; because buffer material is not used, the reverse of the paint-
ing is left visible so that the courier or other museum staffcan examine it
without removing it from the microclimate box.^33
Dimensional movement of different types of wood in closed
cases, with and without silica gel, was studied by Kamba (1993). He states
that the dimensional change of the wood inside the box without silica gel
was less pronounced than that of the wood in the silica gel–buffered case.
Kamba’s studies thus confirmed the results from the tests at the CL, in
which an equilibrium between wood and the surrounding air at different
temperatures was attained without added buffers.
For these reasons the most recent microclimate boxes for panel
paintings at the Mauritshuis and the Rijksmuseum are now made without
any added sorbent material. The buffering role of the panel itself is
re garded as sufficient for the small, enclosed environment of a microcli-
mate box. However, care is taken to ensure stable temperatures around the
microclimate box, whether it is on display in the gallery or in transport
(Wadum et al. 1994). To this end, the research at the CL also showed that
maintaining an open air space of2 cm or more between the microclimate
box and the wall increases considerably the stability of temperature within
the box (see also Ranacher 1994). Thermally insulated transit crates may
maintain a relatively stable temperature inside the microclimate box on
long journeys (Fig. 3a–d).Microclimate boxes that alter the gaseous content
Apart from one very early foray, the use of microclimate boxes with
analtered gaseous content has become popular only in the last decade.
This new interest arose from the need to reduce the deteriorating
effects of oxygen.
The first known attempt to make a microclimate box was in 1892 in
England by Simpson, to protect a painting by J. M. W. Turner in the Victoria
and Albert Museum (Simpson 1893). The characteristics—tailored to fit the
specific painting—ofthis sealed, airtight box were very similar to a modern
microclimate box. Simpson’s box was even intended to be fitted into the
original gilt frame and hung in the usual manner. The front was composed
of glass; the back comprised glass, metal, or other materials. In Simpson’s
box, nozzles were placed at the bottom for attachment to an exhauster,
which could extract air from the box to create a vacuum around the picture.510 Wadum
30 Wadum fig 04 epsFigure 3a–d abcd
Four main types of microclimate boxes: (a) a
box containing a panel and buffer and no
framing, (b) a box encapsulating a framed
panel and buffer, (c) a framed box containing
a panel and buffer, and (d) a framed box con-
taining only a panel.